Air-conditioning and heat pump systems for residential and commercial applications are known to employ modified automotive heat exchangers because of their high heat transfer efficiency, durability, and relatively ease of manufacturability. A typical automotive heat exchanger includes an inlet manifold, an outlet manifold, and a plurality of extruded multi-port refrigerant tubes for proving hydraulic communication between the inlet and outlet manifolds. The core of the heat exchanger is defined by the plurality of refrigerant tubes and the corrugated fins disposed between the refrigerant tubes for improved heat transfer efficiency and increased structural rigidity. The refrigerant tubes may be aligned in a parallel and substantially upright orientation with respect to the direction of gravity. The corrugated fins may be provided with louvers to increase heat transfer efficiency.
For heat pump applications, in heating mode the outdoor heat exchanger acts as the evaporator and in cooling mode the indoor heat exchanger acts as the evaporator. When the heat exchanger is in evaporative mode, a partially expanded two-phase refrigerant enters the lower portions of the refrigerant tubes from the inlet manifold and travels up the refrigerant tubes expanding into a vapor phase as the refrigerant absorbs heat from the ambient air. As the airflow passing through the core of the heat exchanger is cooled below its dew point, moisture in the air is condensed onto the exterior surfaces of the refrigerant tubes and fins.
For certain residential and/or commercial applications, the size of the heat exchanger core may reach a height of over 5 feet. Condensate accumulating on the core can build up to form a condensate column within the spaces between the refrigerant tubes and fins; thereby, obstructing airflow through the core resulting in reduced heat transfer efficiency. Aside from the reduction in heat transfer efficiency, the accumulation of condensation in the core of the indoor heat exchanger is especially undesirable when the indoor heat exchanger is operating in evaporative mode. The velocity of the airflow across the heat exchanger face can reach upwards of 700 ft/min. At these high velocities, the airflow impacts the condensate column and launches condensate droplets out of the core into the downstream air plenums.
It is desirable to have an elegant solution to extract and convey condensate away from the heat exchanger core, to minimalize obstruction of airflow through the core and eliminate the launching of condensate droplets into the air plenum.